Ellen L. Blank
Movement of nutrients through the gut results from coordinated contractions of the intestinal smooth muscles. Gastrointestinal motility is regulated by myogenic, neural, and neuroendocrine input during fasting and digestion. Development of uncoordinated human gastric contractions occurs as early as 26 weeks’ gestation, although gastric emptying is slow and feeding intolerance occurs commonly. Increasing strength and coordination of gastric and small intestinal muscle contractions develop at approximately 30 weeks’ gestation, allowing for enteral feedings by tube. By 36 weeks’ gestation, motility patterns similar to those of term infants and the appearance of coordinated sucking and swallowing allow preterm infants to feed orally.
Motility disorders may arise from abnormalities of any of the regulatory inputs anywhere in the digestive tract. Recurrent signs and symptoms of intestinal dysfunction without any demonstrable obstructing lesion present a diagnostic dilemma. Common complaints include dysphagia, anorexia, heartburn, nausea, vomiting, chest pain, abdominal bloating, abdominal pain, diarrhea, and constipation. These symptoms may occur acutely as a reversible ileus with infection. Postsurgical syndromes such as ileus, duodenogastric (bile) reflux, and rapid gastric emptying seen in dumping syndrome and postvagotomy also are regarded commonly as disorders of gastrointestinal motility.
Chronic intestinal pseudoobstruction is a heterogeneous group of disorders presenting with signs and symptoms of mechanical bowel obstruction without any demonstrable obstruction. Primary pseudoobstruction occurs more commonly in children and may occur sporadically or as part of a familial syndrome. Approximately 20% of cases are familial. Neural or myopathic abnormalities may be responsible. Dysfunction also may occur in other organs containing smooth muscle, such as the urinary bladder, gallbladder, and eyes. The onset of symptoms may occur in infancy or in a previously healthy child.
Secondary pseudoobstruction has a similar presentation but can be explained by another disease process or drug effect. Diseases affecting gastrointestinal smooth muscle include scleroderma, dermatomyositis, systemic lupus erythematosus, amyloidosis, myotonic and muscular dystrophy, and ceroidosis. Hormonal disorders impairing gastrointestinal function include hypothyroidism, multiple endocrine neoplasia type IIB, hypoparathyroidism, and pheochromocytoma. Neurologic abnormalities causing neural gastrointestinal dysfunction include diabetic autonomic gastropathy, Hirschsprung disease, and familial dysautonomia. Miscellaneous disorders that can impair gastrointestinal motility include severe inflammatory bowel disease, small bowel transplantation, Chagas disease, and radiation enteritis. Drugs such as opiates, phenothiazines, tricyclic antidepressants, anticholinergic agents, clonidine, and calcium channel blockers also may impair gut motor function.